A U.S. Department of Justice (DOJ) official has joined the debate surrounding Apple Computer's proprietary digital music technology by criticizing European antitrust activities, but groups attacking Apple are defending their actions.

Speaking in Washington, D.C., on Wednesday, Thomas Barnett, assistant attorney general at the DOJ's antitrust division, warned that forcing companies to reveal their intellectual property stifles innovation. He used Apple as an example, in a nod to growing discontent in Europe regarding the way that music purchased from iTunes is tied to the iPod.

Architects of complaints against Apple in Europe say he's got it wrong. "We're not attacking intellectual property rights but saying they should be implemented in a way which doesn't dictate which player you use," said Torgeir Waterhouse, a senior advisor with the Norwegian Consumer Council.